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WorksheetsCement Process
Total questions: 30
Worksheet time: 23mins
Calcination of material in the range of 600 to 900 Deg. Celsius for the decomposition of CaCO3 to CaO and CO2 is one of the main cement chemical process taking place in the preheater tower?
True
False
What burning zone temperature range (Highest Temperature in Cement Kiln) ?
1300 to 1450 °C.
900 to 1000 °C.
1100 to 1200 °C.
900 to 1100 °C.
Which the type of the following equipment give the highest separation efficiency of gases and dust?
Cyclones
Separators
Gravel filter
Electrostatic filter
Bag filters
The most famous type of mill used in grinding with high production capacity is:
Vertical mills
Ball mills
Horo mills
Roller Press mills.
Cement technology is well known to be one of the highest energy consuming industries, fuel is one of the main components of cement cost, which one has the current highest cost in terms of EGP/GJ;
Natural Gas
Coal and Petcoke
Heavy Fuel Oil (Mazout)
Diesel
What is the average residue on 45 micron for OPC CEM I 42.5 N?
0-10 %
10-20 %
30-40 %
40-50 %
What is the meaning of soundness of cement?
Ability to flow when mixed
Ability to make ringing noise when struck
Ability to form strong and sound structure
Ability to retain volume after setting
Time elapsed from the instance of adding water until paste ceases to behave as fluid is called:
Initial setting time
Final setting time
Intermediate setting time
Absolute setting time
Which of the following is from Quarry operation main KPIs;
Crusher RF, limestone oversize % and clay % in mix
Explosive consumption in gm/ton, optimizing reserve and limestone oversize %
Crusher kwt/ton , crusher PF and Cl % in limestone
Crusher RF , explosive consumption in gm/ton and crusher PF
How is clay overburden treated?
Dumped
Removed to a remote area
Used in rehabilitation
IF its chemistry enable its usage in the plant as an additive in cement mill with cost efficiency, if not, rehabilitation is done
In raw mix composition, the following is taken into consideration except;
Raw mix chemical analysis, total cost, fuel type used
Additives availability, total cost and chemistry targets
Physical properties and chemistry targets
Additives availability, chemical analysis , physical properties and MgO content
For solid fuel selection, the most important properties for choice are;
Price in EGP/ton , supply availability and fuel chemistry including heat value
Fuel heat value, fuel physical properties especially HGI and Environmental approval
Fuel price in EGP/GJ , physical properties and supply on time
The rule of thumb of grinding solid fuel to consider its sieve on 90micron
10% of solid fuel volatile content
30 % of solid fuel HGI content
50 % of solid fuel volatile content
50 % of solid fuel HGI content
What inventory of solid fuel is normally kept in the plant
The more secured stock the best
2 weeks operation stock
6 weeks operation stock
Optimized stock based on production plan and purchasing plan
The main operating parameters of steady operating kiln are;
Kiln preheater exit temp, NOx in main stack , O2 in kiln inlet
Kiln torque, Tertiary air temp and cooler clinker output temp
Kiln speed, ID fan speed, kiln inlet O2
Kiln speed rpm , NOx in inlet and bypass fan speed rpm
The main KPIs for kiln performance are;
Kiln specific power consumption and heat consumption
Kiln UF %
C/K
RF %
Ring formation is from kiln operational problems, it can be monitored through;
Visual inspection on the kiln shell
Kiln shell scanner
Kiln inlet draft
Kiln inlet O2
Flame shape can be controlled by;
Axial and swirl air burner setting
Kiln ID fan and bypass fan speed
Kiln hold pressure
Buner axial and swirl air plus kiln draft
Snow man problem can be eliminated by;
Air blasters operation
Adjustment of raw mix chemistry
Increase kiln speed to the max. possible
Reduce kiln feed
Clinker external storage has the following drawbacks;
Safety issues
Cost of double handling
Clinker temp reduction
Clinker chemistry destroyed
In CEM I 42.5 N , the clinker proportion is mostly in the range of;
75 - 80 %
80 - 85 %
85 - 90 %
90 - 95 %
From the drawbacks of hot clinker grinding;
Mill internals and balls are subject to coating
Mill output possible reduction
Cement temp control difficulty leading to mill stoppage
All of the previous answers are correct
The increase of mill outlet temp has the following risk
Cement high temp. cause dehydration of gypsum
Mill mechanical internals are subject to heat stresses
Cement setting time impacted
All of the previous answers are correct
Slag is widely used in cement industry as it reflect many benefits but it has a major drawback which is;
It increases CO2 emission
It decreases clinker produced
It has high abrasive impact
It replace iron additive as a source of iron
Raw meal to clinker ratio is in the range of ;
1.5 to 1.7
3 to 3.1
0.5 to 0.7
2.1 to 3.1
Heat transfer in the kiln section is mainly;
Cocurrent heat transfer
Counter current heat transfer
Both concurrent and counter current
Splash box is very important in the preheater as it impact on;
Heat transfer between material and gases
Separation efficiency of the material in the preheater
It has an no real impact
It increases gas speed
Dip tube (Inner pipe) is very important especially in;
Middle cyclones
Upper most cyclones
Lower most cyclones
In the area of connecting the movable part (kiln) with fixed part (preheater), there is a tongue to allow material from lowest cyclone to enter the kiln, any problem in this area will lead to;
Increase of bypass dust rate
Relative decrease in clinker output
Non desired material splash
All of the above
C3S is mainly responsible for cement early strength while C2S is responsible for its late strength
True
False
Partially true
